3B Scientific Test Vessel - Handbuch (Seite 10)

10
N is the number of bright maxima and x the separa-
tion between them.
The speed of sound in the medium can now be calcu-
lated once again from the measured frequency n us-
ing equation (2).
Note:
With the U10008 test vessel it is only possible to set up
a good projection of the standing ultrasonic wave at a
frequency of 4 MHz. At 2 MHz and especially at 1 MHz
ultrasonic waves reflected from the bottom of the con-
tainer are superimposed destructively on the imping-
ing ultrasonic beam. Only for 4 MHz waves is the dif-
ference in the path length of the order of several wave-
lengths. At 8 MHz the amplitude of the emitted wave
is too small and also the absorption is much greater
(the absorption coefficient is proportional to the square
of the frequency). This means that no clear standing
waves are produced.
Example results:
Water:
a
1
= a
2
= 4.8 cm, f = 10 cm, n
FL
= 1.33, n
g
= 1.45,
s =3.03 m, n = 4 MHz, x = 8.9 cm, g
1
= 5 mm, g
2
= 4 mm
therefore: λ = 397 µm, c = 1590 m/s
(Table: 1480 m/s at 20°C)
4. Technical details
4.1 Ultrasound generator (U10006)
Frequency:
1, 2, 4, 8 MHz adjustable
Output signal: Sine wave, continuously adjustable
between 5 V
pp
to approximately
65 V
pp
. Can be switched off.
Red control light
Display: 3-digit LCD, one decimal place,
height of digits 10 mm
Monitor signal: TTL, Frequency signal
Laser output: 3 V DC, max. 300 mW at socket
5.5 mm outer Ø, 2.5 mm inner Ø,
Can
be switched off.
Red control light
Dimensions: 256 x 86 x 156 mm
Mains voltage: 115/230 V, 50/60 Hz
Power consumption: max. 60 VA; 5 VA minimum power
(laser and ultrasound switched
off)
Fuse: T 315 mA (230 V) / T 630 mA (115 V)
Ultrasonic transducer
Probe diameter:
27 mm
Active surface area: 2 cm²
Cable length:
1 m with BNC socket
4.2 Test vessel (U10008)
Test vessel:
100 x 100 x 120 mm
Volume: 900 ml approx.
Laser holder: 17 mm internal diameter
Transducer holder: adjustable, designed for the
supplied transducer
Lens on glass slide
Lens slide:
76 mm x 26 mm Glass slide with
roughened gripping surface
Lens: Plano-convex, f = 100 mm
(in air), 16 mm Ø
4.3 Laser diode (U10007)
Beam spot:
< 6 mm at 3 m
Wavelength: 650 nm
Power: < 1 mW, laser safety class II
Supply voltage: 3 V DC
Current consumption: max. 35 mA
Connecting plug:
1 m cable with plug of 5.5 mm
outer Ø, 2.5 mm inner Ø
Dimensions: 80 mm x 17 mm Ø
3B Scientific GmbH • Rudorffweg 8 • 21031 Hamburg • Germany • www.3bscientific.com • Technical amendments are possible